1. Field of the Invention
The present invention relates to a flame-retardant resin composition showing excellent flame retardancy without using any halogen-based flame retardant, as well as to a sealant for semiconductor, using the composition.
2. Related Art Statement
Thermosetting resins typified by epoxy resins, etc. are in wide use in parts of electric or electronic appliances, etc. for their excellent properties. In many cases, flame retardancy is imparted to the thermosetting resins to allow them to have safety to fire. The flame retardancy of these resins has generally been achieved by using a halogen-containing compound such as brominated epoxy compound or the like. While halogen-containing compounds have high flame retardancy, aromatic bromine compounds liberate bromine or hydrogen bromide (these are corrosive) when thermally decomposed and, when decomposed in the presence of oxygen, may form a polybromodibenzofuran or a polydibromodibenzoxine (these are very toxic). Further, bromine-containing waste materials are very difficult to dispose.
It is well known that for the above reasons, extensive study is being made on phosphorus compounds as a flame retardant replacing the bromine-containing flame retardant. Addition of a phosphoric acid ester or the like to an epoxy resin, however, has limited applications because of problems of bleeding and hydrolysis. Further, ordinary phosphoric acid ester compounds having a functional group such as phenolic hydroxyl group or the like cause hydrolysis and liberate free phosphoric acid, which invites conspicuous impairment of electrical properties or reliability.